This application is based on and claims priority to Japanese Patent Application No. 11-123940, filed Apr. 30, 1999.
1. Field of the Invention
This invention relates to a snowmobile and, more particularly to an improved drive belt suspension system for a snowmobile.
2. Description of Related Art
Typical snowmobiles employ a drive belt that is driven by the engine through a transmission for propelling the snowmobile along the terrain over which it is traversing. The drive belt conventionally runs over slide rails that back up the portion of the drive belt that contacts the ground. The slide rails are coupled to a frame assembly of the snowmobile by a suspension system for movement relative to the frame assembly. Conventionally, the slide rails are suspended by front and rear suspension units, each of which load a respective cushioning arrangement. In order to maintain a compact assembly, the suspension units and cushioning elements are generally positioned within the confine of the drive belt.
When the snowmobiles run on rough or irregular terrain, conventional suspension systems prevent immoderate pitching movements of the slide rail and maintain stable and comfortable running conditions for the rider. U.S. Pat. No. 5,667,031 discloses one of such suspension systems. The suspension system shown in this patent has rear suspension arms as well as cushion devices. One end of each arm is pivotally affixed to a frame assembly, while the other end thereof has a slide block that is slideably supported within a slot formed on the slide rail. This arrangement can absorb shocks exerted upon the snowmobile while traversing irregular terrain and restrict the movement of the arm in a limited range. However, the suspension system has a drawback that the slide rail is likely to be damaged by the shock that the slide rail itself receives directly because the slide blocks are confined within the slots formed on the slide rail.
U.S. Pat. No. 5,730,242 discloses another suspension system. The suspension system shown in this patent also has rear suspension arms. Each suspension arm comprises a sleeve and a control bar slideably supported by the sleeve. The sleeves are pivotally coupled with the slide rail, while the control bars are also pivotally connected to the frame assembly. A pair of stoppers are provided on each bar so as to restrict the movement of the bar. Therefore, like the arrangement described above, the suspension system can hold stable running conditions of the snowmobile. This arrangement, however, has another drawback that the bars are occasionally prevented from sliding smoothly within the sleeves.
A need therefore exists for an improved drive belt suspension system for a snowmobile in which a structural member, such as a slide rail, does not directly receive an excessive shock and in which the suspension system ensures a smooth movement of its suspension arms when traversing rough or irregular terrain.
In accordance with one aspect of the present invention, a snowmobile comprises a frame assembly and a drive belt. The snowmobile has a longitudinal axis. A slide rail assembly is engaged with a backside of the drive belt and opposite the terrain engaged by the drive belt for propelling the snowmobile along the terrain. A support device biases the frame assembly upwardly relative to the slide rail assembly. At least one suspension arm is arranged to couple the slide rail assembly to the frame assembly. The suspension arm includes a first member connected to the frame assembly for pivotal movement about a first axis and a second member connected to the slide rail assembly for pivotal movement about a second axis. One of the first and second members is slideably supported by the other. The one supported member has a pair of stoppers that interpose the other supporting member therebetween. The one axis that relates to the other supporting member (either the first or second axis) is positioned in the longitudinal direction between the respective stoppers.
Another aspect of the present invention involves a snowmobile comprising a frame assembly and a drive belt. A slide rail assembly is engaged with a backside of the drive belt and opposite the terrain engaged by the drive belt for propelling the snowmobile along the terrain. At least one support device biases the frame assembly upwardly relative to the slide rail assembly, and at least one suspension arm is arranged to couple the slide rail assembly to the frame assembly. The suspension arm includes a first member coupled with the frame assembly for pivotal movement about a first axis and a second member coupled with the slide rail assembly for pivotal movement about a second axis. One of the first and second members is slideably supported by the other member. At least one stopper is provided for restricting a slideable range of the supported member relative to the supporting member. The axis related to the supporting member is positioned in the longitudinal direction between both ends of the slideable range.
In accordance with an additional aspect of the present invention, a snowmobile comprises a frame assembly and a drive belt. A slide rail assembly is engaged with a backside of the drive belt and opposite the terrain engaged by the drive belt for propelling the snowmobile along the terrain. At least one support device is provided for biasing the frame assembly upwardly relative to the slide rail assembly, and at least one suspension arm is arranged to couple the slide rail assembly to the frame assembly. The suspension arm includes a first member connected to the frame assembly for pivotal movement about a first axis and a second member connected to the slide rail assembly for pivotal movement about a second axis. One of the first member and the second member is slideably supported by the other member along a slide axis. The axis related to the supporting member is offset from the slide axis.
A further aspect of the present invention involves a snowmobile comprising a frame assembly and a drive belt. A slide rail assembly is engaged with a backside of the drive belt and opposite the terrain engaged by the drive belt for propelling the snowmobile along the terrain. At least one support device is provided for biasing the frame assembly upwardly relative to the slide rail assembly, and at least one suspension arm is arranged to couple the slide rail assembly to the frame assembly. The suspension arm includes a sleeve connected to the slide rail assembly for pivotal movement about a lower axis and a rod connected to the frame assembly for pivotal movement about an upper axis. The rod is supported by the sleeve and has a pair of stoppers that interpose the sleeve therebetween. The lower axis is positioned in the longitudinal direction between the respective stoppers.
Further aspects, features and advantages of this invention will become apparent from the detailed description of the preferred embodiment and variations thereof which follows.